Membrane lined tunnel and method of constructing same



Jan. 12, 1937. A, KINZI'E 2,067,493

MEMBRANE LINED TUNNEL AND METHOD OF CONSTRUCTING SAME Filed Aug, 14, 1934 3 Sheets-Sheet l INVENTOR.

hi/lip 14. Maj/ 8 E R-W ATTORNEY.

. jam 19370 v P. A. KlNZlE 2,067,493

MEMBRANE LINED TUNNEL AND METHOD OF CONSTRUCTING SAME Eiled Aug. 14, 1954 s Sheets-Sheet 2 INVENTOR. w /n'lll'pfl. Kg/e BY ATTORNEY.

Jan. 12, 1937. I P. KI'NZIE 2,067,493

MEMBRANE LINED TUNNEL AND METHOD OF CONSTRUCTING SAME Filed Aug. 14, 1934 3 Sheets-Sheet 3 INVENTOR.

Phi/1p A. 5 16 ATTORNEY.

Patented Jan. 12, 1937 lJNlTED STATES PATENT oFFicE MEMBRANE LINED TUNNELZAN'D METHOD OF CONSTRUCTING SAltIE 16 Claims. (oi. 61-45) This invention has reference to tunnels, and the method of forming'the same, particularly for pressure purposes and with reference especially to penstccks and the like.--

The usual method of constructing a penstock in a tunnel for'the purpose of carrying water under heavy pressure has-been, as is being used at the present time in connection with the Boulder Canyonproject of the Bureau of Reclamation, the United States Department of the Interior,'to builda concrete lined tunnel of larger size than the penstock which is to convey the water, and to then build, construct or fabricate within the said concrete lined tunnel a pressure pipe of steel which is of smaller size than the tunnel itself but which is of such cons'truction that it is enabled to withstand the hydraulic pressure which, in the case of the Boulder Canyon project, is approximately 300 lbs. plus. This construction renders it necessary to use a fabricated steel penstock having,

in so far as pressure carrying ability is concerned, practically no relationship tothe concrete lined tunnel except that the latterforms an enclosure for the former throughout its route, and thus there is lost any benefit which might beattained throughuse of the concrete of the tunnel itself as a pressure restraining factor, with the result that the expense of such construction is high in that both the concrete tunnel and the steel penstock enclosed thereby donot supplement each other from thestandpoint of functioning as acontainer for the'pressure fluid stream.

The present invention has, as an object, the provision of a composite structure whereinb'oth the concrete lining of the tunnel, the adjacent rock or other material through which the tunnel is excavated; and. the steel penstock: are interrelated in such manner that they jointly combine to form the pressure fluid carrying 'passage, thus rendering it possible to use a lighter steel plate and at the same time cutting down the size of the concrete lined tunnel which must first be bored through the ground and then lined so that there need be provided only the actual size required for the stream and thus saving an enormous amount of material and labor cost, as will be obvious when it is considered that on the Boulder Canyon project above referred to the size of the penstock' is thirty feet while the enclosing concrete tunnel is fifty feet in some sections and thirty-seven feet at others in diameter inside" its concrete lining.

I am well aware" that the proposal to build metal lined concrete passages is not new; and

that much construction work for non-pressure carrying passages has been'done along this line;

however: the difiiculties to be surmounted" in fiuid' tight, and thus effectually prevent anyl.

gradual escapeof fluid into the seams and crevices of" the" adjacentmaterial, but the inevitable escapeof such fluid would progressively buildup hydrostatic pressures effective, cumulatively, over ever increasing areas until the gradual and ever mounting hydraulic force so generated would finally exceedthat of the resistance capacity; of the earth material and serious rupture would eventually occur.

At first thought it' would appear that adequate' tunnel wall sealing could be easily accomplished by lining the tunnel with waterproofconcrete, or some other suitable material, which would effectually restrain the escape of the pressure fluid'beingtransported within the tunnel and, in certain instances, this actually may be done, but these are the exception rather than the rule; the reason being that the behavier of such-materials, under loads, is not as is usually pictured by the lay mind for, where iron, steel, rock and other similar material are commonly considered as being rigid and unyielding, they does a matter of fact possess the property; cfielasticity' to a greater or lesser degree, and, in'consequence deform and flow within certain limits while under stress; accordingly every load applied is accompanied by a corresponding change in shape or condition of the material to which the load is applied, and while these changes in the dimensions of the materialsafiectedare microscopic where but an inch or two of size is concerned, they become very appreciable when similar intensities of loadings are applied to structures of large size.

As an' example of this, the 50 foot diameter diversion tunnels at Boulder Canyon project hereinbefore referred'to, were originally intended: to serve a," dual purpose, namely, to carry were subjected to this pressure, the elasticity of the rock would, in yielding to accommodate it, open up cracks of approximately width extending longitudinally along the crown of the tunnel bore, and when this occurred, th e=concrete lining would likewise be ruptured and would permit the water under pressure to escape into the crevices of the rock and: there build up pressure over constantly increasing areas, until finally the canyon wallswould' in evitably give Way and be shattered.

To overcome this condition metal linings were examined and it was found that they would .have to be made nearly four inches thick in order to withstand the service required. This was prohibitive.

Further investigations showed a fluid tight lining or membrane would have to expand and contract, or to breathe in response to movement with the rock and the concrete lining as varying pressure loadings were imposed, for, inasmuch as these tunnels would be serving as penstocks to the turbines in the power plant, the varying turbine loadings would be accompanied by rapid and frequent pressure variations in these tunnels and would so produce rapid and frequent changes in their circumferential dimensions, and inasmuch as thousands of such cycles would occur every day it is ,evident that, to prevent failure, the water tight membranes or linings would have to be so constructed as to permit of these rapid and frequent changes in size without fatiguing the metal composing them. 7

Many different forms of construction were examined and found wanting in one respect or another, until finally, it appeared that noreasonable solution would be found, whereupon, the placing of 30 foot diameter steel'pipesuinside and independent of the tunnel walls was adopted.

Subsequently the solution embodied within this application was developed, worked out, and found to be adequate.

In the following objects of this invention are found the affirmative responses to the three prime requisites to an economical and reliable solution of this problem, which area First.To provide a fluid tight membrane which effectually confines the fluid within the tunnel bore without, in so doing, preventing-the complete and free transmission of the hydrostatic loads produced by the confined fluid to the adjacent walls formed by the material through which the tunnel is excavated.

Second.To provide a fluid tight membrane which freely responds to the rapid changes in the circumferential dimensions of the tunnel as varying pressure intensities cause these to change. i I

Third.--To provide a membrane lining, which adequately drains upon its exterior surface. in such manner that, should pressure-fluid escape from within to its exterior surface, that fluid will positively be carried away before it hasan opportunity to gain access to the fissures and crevices contained within the material through which the tunnel passes, and. which likewise thus effectually restrains any tendency for localized pressure, zones to form between the outer surface of the membrane and the encasing material in contact therewith, consequently preventing blistering of the membrane when the pressure on the fluid within the tunnel and its enclosing membrane is released.

Inasmuch as it is not practicable to definitely establish the location of every crack that will be formed when thetunnel is subjected to internal pressure, the expansion joints in the membrane cannot always be individually located at each crack, and in consequence of this condition, the membrane must be so arranged that it will be capable of sliding upon the enclosing andsupporting material without sufficient sliding resistance or friction being developed as to dangerously stress or rupture the membrane as such movement occurs.

j As concrete is one of the most favored and widely used materials employed for filling the annular space between the outer surface of the membrane and the enclosing walls of the tunnel bore, it will be assumed in this description that it is so used herein, and it will likewise be assumed that a relatively light sheet metal such as steel, or wrought iron, or the like, is employed as the material for the fluid tight membrane, it being understood, of course, that other materials than those specifically identified herein may be used without departing from the spirit of my invention.

evident that if the exterior surface of the fluid tight membrane is so treated as to permit it With these objectives in view it then becomes 3 to slide with the least practicable resistance,

and if the coeflicient of such sliding resistance be established by trial, then the product of the internal fluid pressure per unit of area times this coeflicient of resistance, divided into the desired working stress of the material employed forthe fluid tight membrane will give the circumferential distance between the longitudinal expansion joints which must be provided therein,

and with this foundation on which to erect the analytic premises a complete mathematical solution of each installation may be worked out in full detail.

To providethe most favorable conditions for the relatively small circumferential displacements between the exterior membrane surface and the encasing concrete, I preferably cover the membrane with a wrapping of heavy asbestos paper whichis ideal for this purpose as it is insoluble in water, does not oxidize or decompose, and still permits the required sliding on concrete with less resistance than any other commercially obtainable product known to me at the present time.

- In encasing the fluid tight membrane with its expansion joints, asbestos paper wrappings with drainage ropes are employed as lashings retaining the asbestos paper wrappings in place, but

ropes; to compensate for this clogging tendency I impregnate these ropes with a mixture of soap and sugar, or other suitable materials of a readily soluble nature, so that any leakage readily dissolves and leaches out these materials and thus affords easy escape to theimainadrains .provided to carry it-away.

Another object of this invention is the method of placingthe membrane in position. The great size of tunnel penstocks, as now usedin modern power developments, renders itxessential to build such membraneliners'in..progressive stages from the bottoms of the tunnels towards the ceilings, employingjumbo. collapsible forms; to support and carry the relatively thin linings while they are being assembled and then concreted in, after which the forms are collapsed, withdrawn and moved ahead for'the next section, and it is to this method that the present invention also refers.

With the above and other. objects in view there willnow be described particular constructions and methods according to thepresent invention which are'forythe; purpose of disclosing the same in accordance with the requirements of the patent statutes; and which have been illustrated in .the accompanying drawings wherein:

Fig. 1 is a transverse end sectional view through a tunnel in accordance with the present invention;

Fig. 2 is a fragmentary end sectional view enlarged of the means providing for expansion of the metal membrane;

Fig. 3 is a View similar to Figure 2 of another means of compensating for expansion and contraction;

Fig. 4 is a view similar to Figures 2 and 3 of still another means of accommodating-expansion and contraction under pressure;

Fig. 5 is a part section view, longitudinally of the conduit tunnel or penstock shown in Figure 1;

Fig. 6 is an enlarged sectional detail view transversely in the direction of the arrows 6-6 of Figure 5;

Fig. '7 is an enlarged sectional detail view in the plane of the line 'I-'I of Figure 5';

Fig. 8 is a View similar'to Figure 1 of a modilied construction;

Fig. 9 is a perspective-view of a detail of the drainage and expansion means of the construction shown in Figure 8-;

Fig. 10 is an enlarged detail, in transverse section, of the-drainage conduitshown at the bottom of Figure 8.

In detail, the structureof the present invention, as illustrated, may be fabricated by first boring a tunnel in the earth of a suflicient size, in cross-section, .to permit of installing the water tight metal membrane with its associated expansion joints, drainage ducts, etc., and filling the space between the twov with concrete to form a tunnel structure in which the natural substance of the terrain through which the tunnel is bored carries a large pro-portion of the hydraulic load. In the bottom of the tunnel and surrounded by concrete A is a drain channel 2, and parallel therewith, but spaced as shown, are formed, in the concrete, the channels 3, l and 5 for the expansion and contraction-elements to be hereinafter described. Circumferentially embedded in the concrete A forming the tunnel are ropes 6 which are crossed longitudinally by ropes I, this net-work being clearly shown in Figure 5, and the circumferential ropes are looped down into, or have their ends extending into, the drain channel 2, as shown at in Figures 1, 5 and '7. These ropes 6, when the metal liner or membrane. I of the tunnel is-in' place, constitute-drainage passages which relieve, to the channel 2, any pressure whichmight otherwise tend to build up between the concrete A and the metal membrane I.

The. metal membrane or liner I, is built up in sections and there is. provided at the top of the tunnel, in the concrete A, a number of channels 8, 9, III, II, I2, I3 and I4 identical with the channels, 3, 4 and 5 at the bottom. The channels 3 to 5 and 8.to I i accommodate an enclosure or light metal form I5 between which, and the'concrete, is disposed a resilient element B, such for instance, as asbestos paper surrounding the membrane I and initially held in place by adhesive 'or the drainage ropes 6.

Within eachof "the channels and welded to the plate I6, constituting the membrane liner I for the tunnel, is a longitudinally split tubular element II, the edges of the split I8 being welded as at I9 and 29 on each side to the adjacent edges of plates 2I and 22 forming a portion of the liner or membrane I.

The space between the split tubular element II and the light metal casing I5 is filled with loose material, such as shot or sand, so that when the total metal membrane I is fabricated by welding; or the like, so that it lies closely adjacent the concrete, with the exception of such spacing as is afiorded it by, for instance, the protrusion, if 'any, of'the ropes, and the. asbestos paper, the whole metal membrane I is resilient and may breathe or expand and contract to a certain extent so as to distribute its load evenly throughout the concrete encasing the same, and yet should any water accumulate between the metal membrane and the concrete, the pressure will be relieved by the checkered network of ropes forming wicking providing passages eventually directing drainage to the conduit drain tube 2.

With reference to Figure 3, plates 2i and 22 and the element I'I welded thereto as at I9 and 20, are identical with the structure described in connection with Figure 2, but the box like structure designated in Figure 2 as I5 and forming the enclosure for the sand or shot surrounding the split tubular member II, and in this instance indicated as 23, is formed of Z shaped members 24 and 25 Welded as at 26 and 21 respectively, to the outside of the plates 2i and 22 in a longitudinal direction with respect to the axis of the tunnel, penstock or conduit. Overlying the top of these 2 shaped members to close the space between the same, and welded thereto as at 28 and 29, is a cover plate 38. As in the case of the construction shown in Figure 2, the outside of this channel 23, as well as the entire outside of the membrane, isoverlaid with asbestos paper 3I and the ropes 32 in the same manner as is described previously. One important difierence from the construction shown in Figure 2 is the sealing strip 33 which overlaps the slot I8, and is welded longitudinally only to the plate 2I as at 34, the said strip 33 having a slip joint fit with the plate 22.

In connection with the construction shown in Figure 4 the plates 2| and 22, which have been similarly designated throughout the description of Figures 2 and 3, have longitudinally riveted thereto the channel members 35 and 38 secured to the plates 2I and 22 by rows of rivets designated at 3'5 and 38 and which rivets also serve to secure in place the flanges 39 and 46 of the inverted U shaped channel member ll covering the split 42 between the plates 2I and 22 and which on the inside, or pressure side, of the tunnel, penstock orconduit, is covered by the slip plate t3 welded as at 44 to the plate 2| and having a slip joint with the plate 22. The top or open side of the channel thus formed by the members 35 and 36 is closed by a cover plate 44' secured in .place by screws 45 on each side and threaded into the flanges of the members 35 and 36 respectively; here, again, this channel thus formed is overlaid with asbestos paper, or the like, 4%, and the ropes 41 as was the case in the construction shown in bOthFigures 2 and 3.

With reference to Figures 8 to 10 inclusive, the construction is not radically different from that just described in connection with the preceding figures except as relates to the channel members permitting expansion and contraction, and 'replacement of the ropes with other means. In this case the same plates 2! and 22 referred to in connection with the preceding figures and having the split between closed by the tubular element H as in Figure l, are enclosed by the L shape members 48 and 49 forming a channel covered by the cover plate 50, all of which are welded or otherwise secured together, and have inside thereof reticulated material 5! such as fine wire mesh which will retain the shot or sand within the channel; the cover plate 58 as well as the L shape side members 48 and 49 being provided with holes, as shown, and indicated at 52 for drainage purposes. In this instance the ropes of the preceding structures described are replaced with a flexible metallic conduit 53, welded or otherwise secured in place; the box or channel like member, as in the previous instance, being overlaid with asbestos or similar paper 54, and in the bottom channel of this construction and leading to the drain 2 are nipples 55, all of the channels being connected to one another, as shown by this flexible metallic tubing which not only takes the water from the channels themselves but permits the infiltration of water along its length.

In building up this type of construction, the tunnel is first formed in the earth and concrete blocks or other spacing means are provided at the bottom to receive the bottom 30 portion of the cylindrical steel membrane with its longitudinal expansion joints, and the concrete is then placed beneath this portion of the membrane. The side portions of the membrane are then built up in sections and supported while concrete is placed behind the same, leaving the top one-third still to be finished, and when these plates are put in place with their respective longitudinally arranged expansion joints, the remaining concrete between the membrane and the tunnel wall can be put in position by the gun type or other method.

In this way there is built up a metal membrane lined tunnel which may expand and contract as pressure is applied and taken off, and which seals the concrete work and yet is provided with safety means preventing the building up of pressure between the metal lining and the concrete of the tunnel.

In certain materials it will be found necessary to install the supporting lining progressively as the tunnel heading is advanced, especially through ravelly ground or in certain forms of shale which, while quite firm and dense so long as they are protected from the air, disintegrate very rapidly as soon as air contacts them. When conditions of this nature obtain, the concrete, usually placed after the fluid tight membrane sections have been assembled in their final position in the tunnel, is poured prior to the installation of the membrane and the longitudinal recesses to receive the expansion joints of the fluid tight membrane are formed in the concrete, thereby making it unnecessary to provide the metal boxes previously described for encasing these. The membrane units are then installed with their asbestos wrappings pasted to their exteriors and are placed directly against the preformed surface of the concrete lining which has checkerboard grooves formed in it to carry drainage to the bottom conduit, thus eliminating the impregnated lashing ropes previously described.

The space between the longitudinal recesses formed in the concrete and the exterior surfaces of the: expansion joint members of the fluid tightmembrane is filled with sand, shot, or other material which accommodates the slight movements which occur here and which will, at the same time,v adequately support these parts against the internal fluid pressure which they must withstand.

In applying the fluid tight membrane to the preformed concrete'lining as just described, it is essential that it closely contact the supporting enclosing surfaces thereof, and to accomplish this the forms employed to install the concrete are stripped of their drainage groove forming ridges and the members which form the longitudinal expansion joint recesses, and are reerected in radial units with the corresponding units of the. fluid tight'membrane clamped to their exterior surfaces; and after a complete cylindrical section is in place these forms are then expanded by suitable jacking means until the sections of the fluid tight membrane are brought into firm contact with enveloping surfaces of the previously formed concrete, whereupon the membrane sections are joined by welding, or other suitable means as previously described, after which the forms are then collapsed and withdrawn and the process again repeated.

While in the foregoing there has been described specific constructions and methods in connection with the present invention, it will be observed that these may be modified in accordance with existing conditions on the job in hand without departing from the scope of the invention as expressed in the appended claims defining the same; for instance, in connection with the Pierre shales and other similar geological structure, change in temperature is accompanied by the destructive effect upon the shales and thus might require special treatment where joining the plates either longitudinally or along the channels, and it might be impossible to use direct welding as has been described in connection with the foregoing specific instance.

I claim:

l. A pressure tube within an earthen passage inclusive of a pressure resistant concrete lining for the same, and a resilient metal membrane co-extensive with and lying closely adjacent to the inside surface of said lining.

2. A pressure tube within an earthen passage inclusive of a pressure resistant concrete lining for the same, a resilient metal membrane coextensive with and lying closely adjacent to the inside surface of said'lining, and means between the lining and membrane relieving fluid pressure.

3. A pressure tube within an earthen passage inclusive of a pressure resistant concrete lining for the same, a resilient metal membrane coextensive with and lying closely adjacent to the inside surface of said lining, and a drainage network between the lining and membrane to relieve fluid pressure.

4. A pressure tube within an earthen passage inclusive of a pressure resistant concrete lining for the same, a resilient metal membrane coextensive with and lying closely adjacent to the inside surface of said lining, said membrane having longitudinally split junctures lengthwise of the concrete lining, and means between the lining and membrane relieving fluid pressure.

5. A pressure tube within an earthen passage inclusive of a pressure resistant concrete lining for the same, a resilient metal membrane coextensive with and lying closely adjacent to the inside surface of said lining and longitudinally split, longitudinally split resilient means closing the aforementioned splits, yielding means between the concrete and said resilient means, and a drainage net-Work of ropes impregnated with water soluble material and lying between the metal and the concrete to relieve pressure.

6. A pressure tube within an earthen passage inclusive of a pressure resistant concrete lining for the same, a resilient metal membrane coextensive with and lying closely adjacent to the inside surface of said lining and longitudinally split, longitudinally split resilient means closing the aforementioned splits, a drainage net-work of ropes impregnated with a water soluble substance and disposed between the metal and the concrete to relieve pressure, and a slippage element between the ropes and the metal to reduce the friction between the passage wall and metal membrane.

'7. A pressure tube within an earthen passage, the natural walls of which are of a character to withstand the pressure load imposed by the fluid in the tube, inclusive of a resilient sealing membrane of metal cio-extensive with and lying closely adjacent the wall of the passage, means interposed between the passage wall and the membrane substantially eliminating irregularities of the passage wall, and drainage means between the passage wall and said membrane.

8. A pressure tube within an earthen passage, the natural walls of which are of a character to withstand the pressure load imposed by the fluid in-the tube, inclusive of a resilient sealing membrane of metal co-extensive with and. lying closely adjacent the wall of the passage, means interposed between the passage wall and the membrane substantially eliminating irregularities of the passage wall, and means between the passage wall and membrane affording slippage between the two.

9. The method of building a pressure tube of concrete with a metal membrane liner of resilient construction with drainage and slippage means between comprising the steps of excavating an earthen passage, assembling metal membrane liner sections within the passage while spacing the same from the wall thereof and interposing the drainage and seepage means, and then placing concrete intermediate the passage wall and membrane to eliminate irregularities and fix the location of the drainage and slippage means.

10. A pressure tube within an earthen passage, a pressure resistant concrete lining for the same, a resilient metal membrane co-extensive with and lying closely adjacent to the inside surface of said lining and longitudinally split, longitudinally split resilient means closing the aforementioned splits, yielding means between the concrete and said resilient means, and a drainage net-work between the metal and the concrete to relieve pressure.

11. The method of building a pressure tube of concrete with a metal membrane liner of resilient construction with drainage means between comprising the steps of excavating an earthen passage, erecting within the passage a metal liner of resilient construction and coextensive longitudinally and transversely with the earthen passage while interposing drainage means between the same, and then placing concrete between the liner and passage walls to eliminate irregularities.

12. As an article of manufacture, a tubular metal membrane for pressure tunnel lining and having longitudinal splits closed by similarly split resilient tubes welded thereto.

13. As an article of manufacture, a tubular metal membrane for pressure tunnel lining and having longitudinal splits closed by similarly split resilient tubes welded thereto, and a slip joint split closing lip for each split.

14. As an article of manufacture, a tubular metal membrane for pressure tunnel lining and having longitudinal splits closed by similarly split resilient tubes welded thereto,'a slip joint split closing lip for each split, and means enclosinga yieldable material surrounding the said resilient tubes.

15. A tubular structure for carrying fluid under pressure within an earthen passage which comprises a tubular concrete wall coextensive with the passage wall, and a closely adjacent impervious yieldable membrane coextensive with and independent of the concrete and restrained by the concrete against internal pressure deformation beyond the limit of its yieldability.

16. A tubular structure for fluids under pressure which comprises a tubular concrete wall, a closely adjacent impervious yieldable membrane coextensive with and independent of the concrete and restrained by the concrete against internal pressure deformation beyond the limit of its yieldability, and means between the concrete and membrane assisting relative movement.

PHILLIP A. KJNZIE. 

